Introduction

For this activity, you will use the PhET Interactive SimulationCharges and Fields https://phet.colorado.edu/en/simulations/charges-and-fields to investigate an electric field at various distances around a charge. This simulation has both positive and negative charges to place in the field. All charges are 1 nanocoulomb (1 nC = 1 x 10^-9 C).

There is also electric field sensors that can be placed in the field. These sensors give the magnitude of the electric field strength in volt/meter (V/m). Recall from theElectrostatic Presentation https://docs.google.com/presentation/d/1qjZcUNNLC_CTErE1O3kY0_3Du_QtIEuU17KZfkRKkoM/edit#slide=id.p9 that electric field strength is calculated using the following equation:

One volt/meter is equal to one newton/meter (N/m). Electric field strength is a vector quantity, therefore the electric field sensors also give the direction of the electric field.

Materials

An internet-connected computer

Procedure

Part 1 - Electric Field Lines

1. Open thesimulation https://phet.colorado.edu/sims/charges-and-fields/charges-and-fields_en.html. In the upper right-hand corner, check Show Electric-field, Grid, and Values.
2. Take a few minutes to put charges in the field and note what happens to the field lines as charges are moved around.
3. Arrange the charges as shown in the Data Table 1 below. Draw the electric field lines using arrows for each arrangement.
4. Be sure to clear your charge(s) before going on to the next arrangement.

Data

Table 1: Electric Field Lines (15 points)

Data Table 1 continued

Part 2 - Electric Field Strength

1. Make certain all charges are off of the field, and the Show E-field, Grid, and Values options are selected.
2. Place a positive charge on the grid so it is on two dark lines.
3. Place E-Field Sensors at the coordinates shown in Data Table 2 below.(Use the tape measure for distance measurements or your answers for electric field strength will not be sized correctly.)
4. Use the information given by the E-Field Sensors to complete the data table. (Use the first answer in the table to double check your work. Your answer should be close.)
5. Clear the field, and place a negative charge on the grid so it is on two dark lines.
6. Repeat steps 2-3 for Data Table 3.
7. Again clear the field. Place a positive and a negative charge on the grid so they are 2 meters apart, with the positive charge on the left and the negative charge on the right. Assume the positive charge is at coordinate (0,0).
8. Repeat steps 2-3 for Data Table 4.

Data Table 2: Electric Field Measurements for a Positive Charge (20 points)

x-coordinate (m)	y-coordinate (m)	Electric field strength (V/m)	Direction of electric field
0	1	9.4	90.0
0	-0.5
1	1
1	-2
-1	-1
-2	1

Data Table 3: Electric Field Measurements for a Negative Charge (20 points)

x-coordinate (m)	y-coordinate (m)	Electric field strength (V/m)	Direction of electric field
0	1
0	-0.5
1	1
1	-2
-1	-1
-2	1

Data Table 4: Electric Field Measurements for a Positive Charge and a Negative Charge (20 points)

x-coordinate (m)	y-coordinate (m)	Electric field strength (V/m)	Direction of electric field
0	1
0	-0.5
1	1
1	-2
-1	-1
-2	1

Analysis and Conclusions (5 points each)

1. Using the information in Data Table 1, describe the direction of an electric field.

1. Compare the electric field strength in Data Table 2 (with a positive charge) with data Table 3 (with a negative charge).

1. Compare the direction of the electric field in Data Table 2 (with a positive charge) with data Table 3 (with a negative charge).

1. Using the information given in Data Table 4, explain how opposite charges affect the electric field in both magnitude and direction. Where is the electric field reading the largest in comparison to the distance from the charge?

1. Use thesimulation https://phet.colorado.edu/sims/charges-and-fields/charges-and-fields_en.html to create electric field strength vs. distance graph.

1. Watch this videohttps://www.youtube.com/watch?v=wKuqNuzM1oM? What are three things you learned from this video?